Publication Type: | Journal Article |
Year of Publication: | 2010 |
Authors: | Jin, VL, Romanek, CS, DONOVAN, LISAA, Sharitz, RR |
Journal: | The Journal of the Torrey Botanical Society |
Volume: | 137 |
Issue: | 4 |
Date Published: | 2010 |
ISBN Number: | 1095-5674 |
Keywords: | Acer, glycine, Pinus |
Abstract: | Abstract Plant uptake of soil organic N in addition to inorganic N could play an important role in ecosystem N cycling as well as plant nutrition. We measured in situ plant uptake of organic and inorganic N by the dominant canopy species in two contrasting temperate forest ecosystems (bottomland floodplain forest, subxeric sandhills long-leaf pine forest). Seedlings of Acer rubrum L. and Pinus palustris Mill. in floodplain and sandhills forests, respectively, were treated with isotopically-enriched organic N (15N-[2]-13C-glycine) or inorganic N (15NH4+) to examine in situ uptake. We also measured soil organic and inorganic N concentrations to assess the availability of N for plant uptake. Neither species took up organic N as intact 15N-[2]-13C-glycine, but significant root 15N enrichment in both species indicated that N mineralized from labeled glycine was taken up. Free amino-N dominated the total 2 M KCl-extractable N in floodplain (57 ± 3%) and sandhills soils (75 ± 3%), followed by NH4+ then NO3? in both soils. Up to 13% of glycine label was mineralized to NH4+ at both sites, suggesting that the majority of label was immobilized or adsorbed in the soil. Recovery of NH4+ label also indicated strong soil immobilization, particularly in sandhills soils after 24 hours. Although uptake of intact organic N did not occur in either species, N mineralized from glycine was taken up by plants in these two contrasting temperate forested ecosystems.Abstract Plant uptake of soil organic N in addition to inorganic N could play an important role in ecosystem N cycling as well as plant nutrition. We measured in situ plant uptake of organic and inorganic N by the dominant canopy species in two contrasting temperate forest ecosystems (bottomland floodplain forest, subxeric sandhills long-leaf pine forest). Seedlings of Acer rubrum L. and Pinus palustris Mill. in floodplain and sandhills forests, respectively, were treated with isotopically-enriched organic N (15N-[2]-13C-glycine) or inorganic N (15NH4+) to examine in situ uptake. We also measured soil organic and inorganic N concentrations to assess the availability of N for plant uptake. Neither species took up organic N as intact 15N-[2]-13C-glycine, but significant root 15N enrichment in both species indicated that N mineralized from labeled glycine was taken up. Free amino-N dominated the total 2 M KCl-extractable N in floodplain (57 ± 3%) and sandhills soils (75 ± 3%), followed by NH4+ then NO3? in both soils. Up to 13% of glycine label was mineralized to NH4+ at both sites, suggesting that the majority of label was immobilized or adsorbed in the soil. Recovery of NH4+ label also indicated strong soil immobilization, particularly in sandhills soils after 24 hours. Although uptake of intact organic N did not occur in either species, N mineralized from glycine was taken up by plants in these two contrasting temperate forested ecosystems. |
URL: | http://dx.doi.org/10.3159/10-RA-022.1 |
Short Title: | The Journal of the Torrey Botanical Society |
Soil nitrogen availability and in situ nitrogen uptake by Acer rubrum L. and Pinus palustris Mill. in the southeastern U. S. Coastal Plain1
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